The River That Flows Uphill (Sierra Club Books 1987) is my river diary of a two-week whitewater trip through the bottom of the Grand Canyon,
discussing everything from the Big Bang to the Big Brain. It became a bestseller in
German translation in 1995.

AVAILABILITY limited; the US edition is now out of print. There are German and Dutch translations in print.

The River That Flows UphillA Journey from the Big Bang to the Big BrainCopyright 1986 by William H. Calvin.

You may download this for personal reading but may not redistribute or archive without permission (exception: teachers should feel free to print out a chapter and photocopy it for students).

This is a Deluxe edition in an unusual sense: the photographs and sound files are from Leonard Thurmans Grand Canyon River Running web pages. What you get on your web browser is assembled, before your very eyes, using text delivered from Seattle (Washington State USA, near the Canadian border), and pictures and sound being sent from Tucson (Arizona USA, near the Mexican border).

Prologue

Man without writing cannot long retain his history in his head. His intelligence
permits him to grasp some kind of succession of generations; but without writing, the tale of the
past rapidly degenerates into fumbling myth and fable. Mans greatest epic, his four long battles
with the advancing ice of the great continental glaciers, has vanished from human memory without
a trace. Our illiterate fathers disappeared and with them, in a few scant generations, died one of
the great stories of all time.
the anthropologist LOREN EISELEY (1907-1977)

He who calls what has vanished back again into being,
enjoys a bliss like that of creating.
the historian BARTHOLD NIEBUHR (1776-1831)

Navajo ReservationDay 1, about 2:00 A.M.

WHERE DO WE COME FROM, we humans? Darwin called this "the great subject." Even
five-year-old children sometimes ask this question.

That we ask such a question at all is a testament to human consciousness. I somehow
doubt that the desert animals around here, including the two bats cruising overhead, spend much
time contemplating their origin and destiny. We humans love to spin "what-if" scenarios stringing
together various concepts from our memories. With them, we attempt to explain the past and
forecast the future. However, our consciousness can only be as good as the mental images we
conjure up. And memories are surprisingly fragile.

Beginnings, alas, have usually been lost. Though language gives us a great advantage
over our fellow apes in putting our thoughts in order, word-of-mouth doesnt work very well,
down through the generations. The Navajo Indians of Arizona, on whose desert reservation I am
now nursing a cup of coffee in the moonlight, wandered down here from Alaska and northwestern
Canada only 500 years ago, hunting and gathering along the way. They arrived just in time for
the sixteenthcentury Spanish explorers to "discover" them. Their grandchildren were undoubtedly
entertained with stories of the old country and the journey, just as my grandfather Leebrick told
me of coming west in a covered wagon from Virginia to Missouri in 1882. Yet, only 20
generations of grandparents later, the Navajo have now forgotten all about their ancient home in
the Yukon.

The Navajos are not unusual in such forgetfulness. For most people in most times, there
has probably been little notion of history: they think that the world has always been pretty much
like it is now. Except, of course, for a Creation; unfortunately, there are hundreds of creation
myths around the world and there is very little consensus.

Writing changed that status quo. It gives the societies that possess it a window into the
past, though a narrow one. It enabled the Jews to know, 70 generations after their dispersal, that
they once constituted an ancient nation in the Middle East. In the part of the world where
agriculture first blossomed, historical records go back 200 generations in some places; empires
and other plagues can be seen to come and go. Once the idea of a changing world developed,
contemporary clues took on new meaning. In the nineteenth century, the notion that there had
been an ice age arose when geologists tried to explain boulders that had been transported long
distances from their origins, the strange shapes of some valleys and the parallel scrape marks on
their bedrock. They endured scathing skepticism when they reluctantly proposed that mile-high
sheets of ice had moved down the valleys and covered up much of northern Europe, Asia, and
North America. "No common sense," critics complained. But they were right. There may, in
fact, have been several dozen ice ages.

Now we can reconstruct the past in various ways. The French and Spanish cave
paintings give us a glimpse of life 1,100 generations ago at the height of the last ice age. The
remaining preagricultural societies help give us a picture of what life might have been like 400
generations ago, after the ice melted but before settled agriculture got started. For the
present-day Inuits (Eskimos), the last ice age hasnt ended; their traditional life styles help us
imagine how our ancestors might have existed on the ice age frontiers where skillful hunting was
necessary to get through the winter.

Science is now recovering the lost facts about human origins, sketching in dates, places,
and anatomical changes via the stones and bones that survive. While only a limited view of
prehistoric cultures, it has radically revised our preconceptions. The brain has been rapidly
enlarging for about 100,000 generations, 99.6 percent of whom lived a hunting-and-gathering way
of life before agriculture, civilization, and science came along. We are today using that brain for
things entirely different than the tasks that shaped its evolution.

We have found that our roots reach back to a world, of which little can be seen today.
To understand ourselves  our pleasures, fears, abilities, and consciousness  we must
understand what shaped us: our ancestors way of life and the challenges they faced.

Though it might be a coincidence, the human brain has been enlarging ever since some
crazy fluctuations in the Earths climate started to occur about 2 to 3 million years ago. After
many millions of years of a cooling and drying trend, the Earth began to build up ice in its
northern latitudes, covering as much as 30 percent of the land surface; this was an unusual
development because the earth has been without polar icecaps for 99 percent of its history.
About every 100,000 years, some of the accumulated ice melts off; then the drift back to ice
resumes. This has been going on for several dozen cycles, each icy period pushing the more
highly selected frontier population back into competition with tropical populations, each warm
period providing an opportunity for the survivors on the frontiers to gradually enjoy a baby boom,
then fading into another squeeze-and-expand cycle.

During this odd 2 to 3 million year period since the climate began to fluctuate, one
species brain underwent what was, by the standards of evolutionary biology, an extraordinarily
rapid growth. For some reason  and the rapidity suggests that it was a compelling one  our
brains more than tripled in size. Thats 3.6 times larger than the brain that sufficed for the other
apes during the same time period. Why?

Thats perhaps the key question, and it has emerged after millennia of humans sitting out
at night under the stars, wondering what life is all about, from whence we came. The "great
subject" is what stirs my thoughts tonight, sitting here above the Colorado River in the moonlight,
perched on a great slab of sandstone in the desert and warming my hands on a coffee cup. The
nearly-full moon is about to set in the southwest and, so close to the mountainous horizon, it
appears huge and yellow to me, dominating all else.

Yet a moment or two after touching the mountains, the moon is gone. The stars come
out. The hour is late enough on this summer night that some of the winter constellations can be
seen rising in the eastern sky.

Many minds, stimulated by similar sights, have pondered our origins but pure thought
cannot make much progress. Modern humans have many more facts and concepts to aid their
contemplation, and we better understand the nature of consciousness itself, why and how we
think.

We have arrived at the refined version of the question, "What caused brains to enlarge,
to distinguish humans from apes?", only because a few intermediate things happened to aid our
thinking, such as writing and science. Writing made possible the accumulation of facts over the
generations. A settled life allowed techniques to progress.

Facts and techniques aid human consciousness in its attempts to make up stories: we
take mental images from past and present, string them together with various future possibilities,
and wind up with "what if" scenarios. We then "think it over," trying to see what might go wrong
with a plan  and so we discard most such plans before ever acting, thanks to our quality
judgments. We make choices, and live with them.

This ability to simulate the real world inside our heads gives us an enormous advantage,
both keeping us out of trouble and allowing us insights which lead to new ways of doing things.
To call them plans is to emphasize only one of their uses; I just call them scenarios. We imagine
doing something, see how it plays. We like to make up stories, see how they sound.

Science, too, accumulates facts and techniques, but by making consciousness into a
group activity, refines it even more. A scientist struggles to comprehend the known facts and
ideas about some concept, thinks up a scenario or equation that seems to account for most of the
known facts, and publishes this theory for everyone to see, and then we all (originator included)
attempt to poke holes in it. In so doing, we evolve a better explanation. This back-and-forth
fitting procedure (similar to a carpenter setting a door into a frame), rather than the usual
textbook nonsense about precise logical deduction, is what the "scientific method" is all about.
Creating a scenario may be best done inside a single head; trying to find exceptions to the scenario
is surely best done by many heads.

Pondering this, I can see that the time is coming  and soon  for a comprehensive
biological theory of human origins. Only in this last generation have most of the known facts
about human prehistory emerged. During the same 25 years, our knowledge of animal and human
brains has also expanded enormously: we understand more about how mental images are formed,
more about the fragility of our memories and how they can fool us, more about our feelings, more
about how our brains influence the health of the rest of our bodies. We neurophysiologists can
now even conceive mental images about the inner workings of the human brain itself  and even
construct scenarios for how the brain makes up scenarios. A lot has happened. In very
fundamental ways it affects how we think of ourselves  and on an everyday basis, not just when
we find ourselves contemplating the moon setting behind mountains on a starlit night, as the
moonlight dims and the Milky Way begins to emerge from the darkening sky.

We still dont know why those evolutionary changes occurred, but were getting close to
providing a detailed scenario that would seem to answer that crucial question about brain size 
and a few related ones as well. Various experts now know enough to make some educated
guesses about how humans happened, to spin some scenarios that fit the facts  if one can get
them to talk about it.

Our new [anthropological] origin beliefs are in fact surrogate myths, that are
themselves part science, part myth.... People clearly want to be free to choose their evolutionary
origin stories. Bear this in mind as you read this and other accounts of human evolution.

the archaeologist GLYNN LLYWELYN ISAAC (1937-1985)

It usually takes a special setting to get scientists to speculate, off the record, about what
isnt yet certain. A long river trip through the Grand Canyon is just the sort of setting in which it
might happen. On the river and around the campfire, inundated by the evolutionary stories told by
the Grand Canyon itself, will be a good place to discuss these tentative scientific versions of the
old creation myths.

Lees Ferry aerial view looking south along Marble Platform as the Colorado River cuts into it, from Leonard Thurmans Grand Canyon River Running.

Marble Platform OverlookDay 1, Sunrise

THE HIGHWAY EMERGES from a narrow cut in the pastel rocks of the painted desert. From
the edge of the cliff, the view opens out and down. Far below the flat desert of the Marble
Platform stretches out toward the southwest as far as I can see, with the shadows of early
morning seeming to elongate it. The Grand Canyon, the greatest evolutionary spectacle on our
planet, is on that distant horizon.

Some distance upriver from the Grand Canyon, the Colorado River begins its descent
through the layers of our biological history. This happens in a narrow canyon, somewhere just
below where I am now.

Hiking away from the road into the mountainous desert, I felt the fresh breezes of dawn
touch my face. As I approached the precipice, the view opened to the north, revealing a majestic
horseshoe of cliffs, the cornucopia out of which the flat Marble Platform seems to flow.

I am now sharing the viewpoint with four birds preoccupied with their early morning
chatter, quite oblivious of me writing in my river diary. The morning sun is shining on the cliffs
across the way. The shadow line of the new day starts to creep across the Marble Platform
toward me as the earth slowly rotates, taking me with it.

Morning in the painted desert: the incredible red-orange and blue-gray of the rocks,
enhanced by the special warm light of the sunrise, the spotlighting, and the shadows. The best
time of day, worth the all-night journey to get here on time.

The Colorado River, which carved the Grand Canyon, is out there somewhere in the
middle of the horseshoe, heading down toward its most grandiose achievement to make a few
more minor alterations in the Canyons sculpture. The Colorado is not a small river but one of the
largest in North America. Yet even from this grand viewpoint there is no river to be seen.

Back up the road, I glimpsed the river by moonlight, heading this way. Yet the Marble
Platform seems devoid of rivers, as well as of the trees, sheep, cattle, fences, cultivated fields,
houses, towns, and everything else that tends to grow up around rivers. If I sit so that the edge of
the cliff obscures my view of its lone highway, the Marble Platform and its surroundings look like
a scene from a planet unscarred by humans. Were it not for all the cactus and birds near me on
this cliff, Id say that the view was of a planet untouched by life.

I see only natural scars: the surface of the Marble Platform is interrupted by giant,
ragged-edged cracks that descend down into the planet. One crack is the Marble Canyon of the
Colorado River, predecessor to its Grand Canyon; the others are the side canyons that lead down
to the river, carved by the runoffs of the occasional summer thunderstorms. The river is hidden
from this vantage point because it has dug itself a very deep trench during the last 30 million years.

The limestone of the Marble Platform was laid down about 250 million years ago, near
the end of the Paleozoic era. The land masses and sea floors were then rearranging themselves
into just one big continent, Pangaea, surrounded by one big ocean, Panthalassa. The rock
underfoot up here on the overlook was formed about 200 million years ago, early in the dinosaur
days of the Mesozoic, when Pangaea was beginning to break up into what became our present set
of smaller continents, but before theyd yet wandered very far. As I stood up, I accidentally
kicked loose a Mesozoic rock, which promptly fell down toward the Paleozoic. I heard it
ricochet down through the ages.

NOT ONLY IS THE RIVER HIDDEN, but even the cracks disappear when I descend the
EchoCliffs Monocline and drive along the Platform.

Untouched by life? I can now see that the Platform has a scattering of desert scrubs,
but even the local bedrock has been made by life itself. Limestone forms at the bottom of the
ocean when the little floating animals die and their calcium-containing bodies sink to rest. And
even the other half of the calcium carbonate in limestone was largely contributed by life: the
carbondioxide, CO2, breathed out by animals may, if not recycled by plants, make its way into
forming this nice hard rock. Limestone isnt so much an inanimate object, like the lava pushed up
from the depths of the earth, as it is ex-animate.

The road ahead rises and falls a little as it works its way around some of the minor hills
in what, from up atop the cliff, looked like a flat surface. Another misapprehension exposed. I
find that looking up from the road is very distracting, since I am surrounded by the horseshoe of
cliffs, their layers a pale pastel rainbow of colors dominated by reds and browns. There is no hint
of the dramatic in the desert floor. Then, at the bottom of one of those little dips in the roadway,
the highway swings to the left around some rocks  and right before me appears an enormous
crack in the earth, as wide as a superhighway corridor. There is nothing subtle about the way the
Canyon greets its guests.

To the early Spanish explorers coming up from the south, confronting the canyon must
have been a tremendous shock, since they were not forewarned by the almost aerial view of the
cracks that I glimpsed from atop the cliffs. Some conquistadors horse probably stopped so
suddenly at the sight of this gaping hole that the rider was in danger of pitching forward over the
poor animals head. Once the riders collected themselves and ventured on foot to the edge, they
would have seen that there is water in the midst of this desert; indeed, quite an amazing amount of
water: probably the largest river theyd ever seen. But getting down to the water is like
descending the outside of the Statue of Liberty from the torch to the waters of New York harbor.
Then there is the little problem of getting back up again. Such is an explorers life. Fortunately, I
know the easy way down to the water. Its at the base of the horseshoe, a mere 7kilometers
upriver from here, at the old nineteenth-century river crossing place called Lees Ferry. It is about
the only easy way down to the river in the entire state of Arizona. All the long float trips down
the river must cast off from that one beach.

Lees Ferry: the only beginning. Just as we count time from the beginning of the
universe, so is Lees Ferry the place from which all distances along the Colorado River are
reckoned. Indeed, when they ran out of fancy Spanish, Hindu, and local Indian names for all the
subcanyons of the Grand Canyon, they just gave names such as 75 Mile Creek and 220 Mile
Canyon, using the distance downriver from Lees Ferry to describe the place.

The ferryboat was replaced in 1928 by the Navajo Bridge. This two-lane arch bridge
looks like an antique. It peaks up in the middle just like the earliest iron arch bridges in England.
It is an exaggeration to say that it looks like a pair of hands folded in prayer, meeting above the
river, but the hinge in the middle of the span is designed to allow it to rise up higher when the
afternoon heat expands the steel.

To the properly observant, the bridge could serve as a giant Texas-sized thermometer:
the hotter it gets, the more peaked it looks. One drives slightly uphill to the middle, crosses the
peak, and drives down the other side. But I stop, straddling the peak. I turn off the motor.
Silence. Its not my natural perversity that makes me halt, merely the view. The signs prohibit
stopping, but I have yet to see another vehicle on the highway at this hour.

It is as if I were the only person on this world, a visitor exploring a strange and beautiful
planet, seeing occasional relics of an ancient civilization and its primitive technology, listening to
the sounds of its winds and birds, smelling its natural odors without the overlay of civilizations
everyday pollution. There is a breeze flowing upriver, brushing past me as I lean over the old
railing. A pleasant breeze, indeed.

Thirty stories below is the Colorado River. The canyon is about as wide as it is high. A
box canyon. The precipitous walls seem brown; the river appears a dark mint green in this
shadowed light. Along both sides of the river, clumps of greenery grow on the occasional sand
beaches.

Rivers rarely flow in a straight line for very far, given their tendencies to meander, but
for a kilometer or more in each direction from the bridge, I can see along the crack until the river
bends out of sight. The water is flowing much more quickly than I would have guessed.
Something splashes near the left shore, and I look carefully for more activity. Beaver? Rocks
falling? Fish jumping? But it isnt repeated.

Thats a different world down there. Many birds fly over the river, undoubtedly
collecting insects. Sometimes the swallows (or are they swifts?) ascend halfway up a canyon wall
to disappear into a hole, probably to feed a hungry family. Up here on the bridge, one is a
spectator, a passer-by in the manner of an airplane passenger examining the terrain below. Ive
come closer to the river than when I was up on the cliff, but Im still detached. Literally, above it
all. Only the breeze, the smells, and the faint sounds of the river below serve to make me feel a
part of the river environment.

Such distancing often happens today. Our civilization takes us far away from the
elementary sounds and experiences of our hunting and gathering ancestors, leaves us out of touch
with our ancient preagricultural roots. Evolution shaped us from prehumans to humans over at
least 100,000 generations; the 400 or fewer generations that weve spent away from the hunting
and gathering life style probably hasnt changed our gene pool very much. Our deep roots are to
ice-age tribes; although we seem extraordinarily flexible and adaptable, our civilized behaviors are
inevitably an overlay, a frosting that may sometimes be spread too thin if it is not well anchored in
classic ice-age behavior patterns. Getting away to the wilderness occasionally can be a way of
watering those roots, firming up the connection to the overlying high culture, preventing
dislocations.

The sun has finally peeked over the top of Echo Cliffs. The shadow line has reached the
canyon. Scattered clouds tower over the cliffs, backlit by the rising sun. Mountain sunrises and
desert sunrises have always been my favorites. And this is mountainous desert. By the time the
sun is overhead today, a group of us should be floating down the river beneath this spot. And
probably looking up at this bridge. Tourists will wave at us. The Navajo Bridge will be about the
last well see of civilizations monuments for two weeks. There are no roads reaching the river for
225 miles, no fences, no billboards. Its a wilderness, totally unlike the Grand Canyon glimpsed by
millions of tourists from up on top, behind crowded railings.

The best we can do  if we want a journey backward in time, to see the mileposts in the
evolution of intelligent beings, to take a voyage to the origins of life itself, if we want to try to
piece it all together  is to take ourselves to the bottom of the Grand Canyon. There we will find
rocks of great age, we will find fossils, we will find the dwellings of Stone Age peoples. We will
find the land much as our ancestors experienced it, during all those untold generations when
prehumans were being shaped into humans. The dimly remembered world from which we
somehow took flight.

Such a journey requires some time. The best way is to float down the Colorado River,
taking several weeks to investigate the rapids by boat, the side canyons on foot, the waterfalls by
inundation. With, of course, the right companions.

Day 1

Tell me to what you pay attention
and I will tell you who you are.
JOSE ORTEGA Y GASSET

What was left was the incredible view. This is indeed painted desert
country. Not for their edibility are the lower rockwalls called the Chocolate
Cliffs. The dark red ones above them are the Vermillion Cliffs and,
somewhere unseen over the horizon, are Kodachrome Basin and Rainbow
Plateau. Reds and oranges and browns occur in various combinations, often
streaked with iridescent metallic colors. Different shale layers are colored
blue, purple, green, pink, gray, maroon, and brown.

This panorama forms a horseshoe encircling the view back upriver.
The river takes such a sharp S-shaped bend just before Lees Ferry that one
can hardly see its canyon. Looking upriver seems a dead end. The
Colorado River thus appears to come out of nowhere, arising fully fledged
from the base of the cliffs.

Setting off the red cliffs from the racing green water is a white
high-water line bordering the river, much like the lines that delimit other
highways. All of this contrasts with the greenery along the Colorados
shoreline, the super-green of the willows and tamarisk. People who havent
experienced the grandeur of the canyon often refuse to believe a picture of
it  they assume some trick of color photography. You just have to see it
for yourself.

The Colorado moves along at a good clip, generating a welcome
breeze. We often dont row but just float along. To keep up with us,
someone would have to jog at a good pace along the shoreline. Ashore we
were uncomfortable in the hot, still air as we waited for the last of the
packing to be done and the last calls to be made from the lone telephone
booth with its eavesdropping lizards. Lizards are advanced animals that
have the good sense to take shelter from the midday sun.

Now we have the breeze. The windwaves pitter-patter against the
bottom of our boat as we pass the confluence with the Paria River. The
Paria comes down from Utah, draining the waters of Bryce Canyon into the
Colorado.

I EXPLORED THE PARIAS CANYON this morning while waiting for
everyone else to arrive. In most places, the Paria (which rhymes with
"Maria") is a muddy creek almost narrow enough for me to jump across,
though I wouldnt want to be caught in its narrow canyon during a flash
flood. By comparison, the Colorado is a torrent, as wide as a six-lane
highway. The Parias muddy waters slide in along the right bank of the
Colorado, mixing like cream poured slowly into a dark mint tea.

There were lots of lizards along the banks of the Paria, jerking their
tails about, scurrying among the rocks carried down by the Paria in its more
forceful moments. Many of the lizards seem to wear collars, a dark ring
encircling their necks. Surely they were therefore Black Collared Lizards.
But no, I find that they were Yellow-backed Spiny Lizards. So says the
river-runners blue bible, Larry Stevens invaluable waterproof book The
Colorado River in Grand Canyon: A Comprehensive Guide to its Natural
and Human History. Authors who have been published in hardcover,
paperback, and book club versions now have a new ambition: to see a
waterproof edition of their works, truly durable.

All of the Colorado boatmen Ive met are knowledgeable and versatile,
but Larry Stevens carries things to extremes: hes artist, author, publisher,
photographer, biologist, boatman all rolled into one. Mr. Renaissance Man.
But, what with his Ph.D. thesis research keeping him too busy, hes not on
the river this summer. Happily, another biologist-boatman, Alan Williams,
is on this crew  he caught me up on the progress of his thesis research
while we were loading the boats. An ecologist, he studies how cottonwood
trees wage psychological warfare on attacking aphids. They make 10
percent of their leaves so attractive to aphids that the tiny insects will fight
each other to the death for a standing-room-only spot on a tasty leaf, thus
minimizing the damage to the other 90 percent of the leaves. And if you
think thats wild, another ecologist showed that an attacked willow tree
releases a "war cry" odor that alerts the downwind willows to the invaders
so they can mobilize their tasty defenses in advance. And I used to think
that plants were stupid. I doubt that even lizards are that socially-minded.

The lizards are doing pushups. They run around, then they stop and
do pushups for awhile. Not only does their head bob up and down, but their
whole body with it. This happens when two lizards meet. A lizard will blow
itself up to look bigger than it really is, then knocks off a snappy set of
stiff-body pushups that would make a army drill instructor proud. The
second lizard responds with a similar act of its own. The two lizards then
go their own ways, back to the serious business of finding food and mates
while the sun shines, before darkness (or too much sun) forces them into
quiescence.

Lizards are distant cousins of ours. We shared a common ancestor
with them about the time the base of the local cliffs was laid down. The
earliest reptiles date back to 340 million years ago, offshoots of amphibians
like frogs who were less firmly committed to life on land. The mammals
started their own act soon afterward.

THIS BOAT is carrying us down through the ages, the rocks on the left
bank getting older by the minute. Indeed, by millions of years each minute.
Our vehicle is an inflatable descendant of a dory, crossed with a life raft.
Racetrack-shaped like the classic life raft, it is the length of a full-size car
and has two inflated crosspieces dividing the boat into three compartments.
The rubber (actually neoprene) is stressed to elevate the two ends
somewhat, a bow being helpful when crashing into waves, two bows being
better than one where rapids may spin the boat around. Two passengers sit
forward, two aft, and the boatman with his oars takes the elevated perch in
the middle. A rectangular aluminum frame outlines the middle compartment,
holding the oarlocks. We carry all of our provisions for the 14 day journey.
The boatmen are all pros; the rapids of the Colorado River are the premier
white water of North America, no place for amateurs to practice.

In back of us is a great natural amphitheater, a panorama of varicolored
cliffs. The blue sky is scattered with fluffy white cumulus. Soon we float
into the Canyon proper, with walls rising up out of the river to enclose us,
first on the left bank and eventually on the right as well. The rocks in the
walls are about 245 million years old, Paleozoic limestone left over from an
ancient seabed. They contain fossils of fish and reptiles, but theyre a little
too ancient to contain evidence of the dinosaurs. The Mesozoic layers from
maybe 220 million years ago, which used to sit atop the canyon walls, were
eroded away long ago. But the dinosaur layers are still to be found in the
Vermillion Cliffs behind Lees Ferry. And the birds are somewhere above all
that, starting at about 200 million years ago. The fossil birds, that is  the
present-day descendants of those Mesozoic birds are flapping all around us,
catching insects.

The canyon walls keep rising at a prodigious rate. We were on the
river for less than an hour before we saw the peaked bridge spanning the
gorge, thirty stories up. It provided a momentary bit of shade in midriver,
then we floated clear of its shadow. We didnt even look back to say
goodbye to this last vestige of the familiar.

There is something touching and heroic About the early Mesozoic. CLARENCE DAY

SURPRISE  in the shallows we saw a great blue heron lumbering along
with its swiveling gait. That bird could have served as the artists model for
the winged dinosaur; it was almost as tall as one of us, standing perched
atop a rock. Then it flew away gracefully, in slow motion, not as ungainly
as one somehow imagines a pterodactyl to have been. At least the heron has
feathers. They do improve flying, judging from the aerial acrobatics of the
swifts and swallows that flit around our boats, skimming along the wavetops
in search of insects. We spent some time craning our necks to look up high
on the canyon walls, trying to spot the swallow nests in little cracks in the
rocks.

There are also big, glossy-black ravens perched on some rocks nearby.
Unlike the smaller crows, ravens have shaggy throat feathers, similar to the
ones on the tips of their wings. They argue with one another, sounding
cr-r-ruck in annoyance. Ravens are much larger than crows, more
the size of seagulls. The boatman in the neighboring boat has apparently
told a raven story, because several of the neurobiologists have started to
respond with their own stories about smart birds.

I once heard of a nature-film producer up in Seattle who had observed
some of the northwest crows that frequent the beaches practicing an
ingenuous form of shell-cracking at a ferry dock. Clams protect themselves
against predators by a muscle that holds the half-shells firmly closed. I
suppose that one could use a pry bar, but the crows have instead found ways
of simply shattering the shells. Before the ferry would arrive, the crows
would fly in carrying some clams extracted from the nearby beach at low
tide. The Great Clam Airlift! They would then line up the clams on the
pavement, right in the path of the cars coming off the ferry. Not
surprisingly, the departing cars ran over the clams. After the cars passed,
the crows would swoop down to eat the innards. Crows have rather large
brains; even though they themselves are about the same body weight as an
adult rat, their brains are five times larger.

Gulls are also clever at opening shells: they have been known to carry
shells aloft and drop them on a rocky area. In this way, gravity becomes a
simple but effective tool. If a shell doesnt crack when first dropped, the gull
will pick it up and carry it aloft again, repeating this dozens of times until
getting to the food inside. While it obviously works best if there are rocks
below, Ive also seen gulls repeatedly drop shells on an ordinary sand beach
at low tide; the impact on hard, wet sand eventually seems to work, after a
few round-trips.

It isnt just coastal birds that have the shell-cracking idea, either. The
Egyptian vulture does it in the African savannas, carrying ostrich eggs aloft
and then dropping them. If the egg is too large to carry, the vulture has
another scheme: it carries a rock aloft and bombs the egg. This was
observed in the middle of the nineteenth century, long before humans
re-invented bombing.

Ravens bomb too. Scientists who were inspecting a raven nest halfway
up a cliff face were being "mobbed" by the frantic parents. Then some rocks
came falling down. The scientists at first wondered if they were just loose
rocks, knocked free by the unhappy parents. But, when they retrieved the
rocks, they found a telltale ring of organic matter which demonstrated that
the ravens must have pried half-buried rocks out of the ground atop the cliff
and then dropped them; the bombing was no accident.

We neurobiologists enjoy talking science, especially about our
specialty: how brains work. It isnt a workaday subject, to be left behind on
vacation, but more like a hobby in which we continually indulge ourselves.
Some of us specialize in humans, others in monkeys, and quite a few study
the primitive brains of various invertebrates. Some have medical school
backgrounds, others zoological or anthropological or psychological. This
mix should help us to understand the foundations on which brains are built,
as together we have quite an evolutionary perspective. The Grand Canyon,
of course, inundates us with evolution. Its in the walls surrounding us, layer
upon layer. And the layers are still growing, higher and higher.

"Some of Darwins finches in the Galapagos Islands use tools, you
know," Dan Hartline volunteered. Hes an old friend from Hawaii, another
neurobiologist. "The finches down there are all probably the descendants of
just one species of finch, blown west from South America. All it takes is
one animal blown far out to sea to start colonizing an island chain."

"One animal is going to get pretty lonely  doesnt it take two animals
blown to the same island?", someone asked.

"All it takes is one pregnant female," Dan replied, "and a little incest.
Pretty soon, there were lots of the species. And then that first species
subdivided into a whole series of new species, each with a different beak
shape corresponding to the food they eat. Some have thick beaks for
seed-cracking, others have long skinny beaks, handy for poking into cracks
in a tree trunk and catching the insects that live down there. As we say in
the business, the finches have diversified."

"The Tool-Using Finch doesnt have a particularly long beak," he
continued, "and certainly doesnt have the long tongue that a woodpecker
uses to probe inside the hole. But he still gets the insects. He finds a twig
or a cactus spine and holds it in his beak, pokes it down the hole, and the
insects start crawling all over the stick. He pulls the stick out and eats the
insects. Now I think thats pretty clever  thats just like chimpanzees,
fishing for termites by poking a stick into a termite nest."

Islands are a great place for seeing evolution in action. Hawaii, for
example, is filled with tiny fruit flies. The islands themselves arent very old,
but in that time the flies have diversified even more massively than Darwins
finches.

"But arent there lots of problems with evolutionary explanations like
that?", someone asked from the neighboring boat. "From what I read in the
papers, Darwin was wrong."

"Itd be very surprising if he wasnt wrong about something,
considering the massive detail of his writings," I answered. "But Darwin
was amazingly correct, considering that no one knew about genes in 1858,
and none of population biology had been done yet. What he didnt guess
was the detailed mechanism of how the genes changed to create a new
species out of an old one. But youve got to distinguish between if
evolution has taken place, and the details of how and where and when it
took place."

"Evolution is a very straightforward conclusion, drawn from two
observations," Dan Hartline explained. "First, every individual has a parent
or two. So far as we know, that has always been true  linking us to the
past in an unbroken chain. Second, for each and every species, there was a
time when it didnt exist. Together, these two things tell you that evolution
has taken place, modifying some ancestors of a different species into the
species present-day form."

All this was obvious and widely known even before Darwins time.
There are other "explanations" but they are  literally  unnatural. "For
example," I added, "there are birds all around us here on the river. But there
are no bird fossils in those walls of the canyon  those rock layers are too
old, laid down when the fishes and amphibians were still the dominant forms
of animal life and the reptiles were recent inventions. But if you go up north
in Utah, where I was yesterday," I said, pointing back upriver, "youll find
layers of the Earth from much more recent times which havent been eroded
away yet. And theyll contain fossils of what look like modified primitive
reptiles  birds, as well as dinosaurs. Go further north, up into Montana,
and you can even find some bones of the early primates. So, while birds
didnt exist before 200 million years ago, surely the first birds had parents
too, dinosaurs that didnt quite fly."

"Dan, pardon my ignorance," someone volunteered, "but did you say
that an individual could have only one parent? I guess that in high school
biology, I pretty much thought that it took two."

"Maybe you were fixated on sex at the time," someone else kidded.

"There is a tendency to confuse sex with reproduction," smiled Dan.
"But having two sexes happened only in the last third of our biological
history. And the old-fashioned ways  such as budding-off and spores 
still work in many species."

"You mean clones?"

"Thats still another way, though I dislike the word these days, ever
since the popular press got hold of it and created newspaper-selling
headlines about how Hitler could have been cloned."

"So who first invented flying?", asked Dan Richard, sitting up front in
our boat. We have two Dans. This ones a lawyer, the legal counsel to the
governor of California. "I fly sailplanes, and Ive always wondered how
flying got started. Were the flies the first to fly?"

"Probably," I responded, "though not the usual two-winged flies that
you swat. Theyre a streamlined version of more traditional four-winged
insects, having suppressed the genes that make the second pair of wings just
as the chickens have suppressed the genes that make teeth. But flying itself
goes a long ways back. Its been re-invented so many times that it makes
you wonder if even the insects were the first. There were flying dinosaurs,
such as the pterodactyls, although their reptilian ancestors probably didnt
fly. The birds did it with feathers rather than just skin on their wings.
Among the mammals, the bats used skin on their forelimbs to make a wing."

"And all sorts of other mammals can glide between trees," Abby noted,
"using folds of loose skin that they stretch out tight by sticking out all four
legs, making a kind of parachute."

"Did you know that besides the gliding squirrels and the flying fish,
theres even a gliding snake?", volunteered Dan Richard. "I saw it on
television. Down in the tropics there is a snake that eats insects that live up
high in a tree. He climbs the tree with the aid of scale-like protrusions on his
underside. When he has picked one tree clean, theres this little problem of
backing down to the ground and climbing another tree. So instead he casts
off, flattens his body into a ribbon like a boomerang, and glides between
trees. Theres even a parachuting spider."

"Jumping between trees is basically a behavioral invention," noted Dan
Hartline. "Behavior precedes form, as Konrad Lorenz once said. Only later
does anatomy get modified to make the behavior less dangerous and more
efficient. So those animals with extra body skin on their legs are able to
glide better, suffer fewer injuries, eat more insects, leave behind more
flabby-skinned offspring than their competitors. Thats natural selection 
there are just lots of variants within a species, and some succeed better than
others."

"It seems only common sense to us now," I commented. "But it took
many decades after evolution itself was well known for someone to stumble
upon this selective survival as a mechanism for evolving new species.
Variations, then editing. One of Darwins contemporaries said something
like How extremely stupid not to have thought of that before!"

Mile 8Badger Rapid

THE LONG RUN IS POSSIBLE only if we consistently take care of the
short run. And so our talk of evolution ceased in favor of paying attention
to a consuming interest downriver.

Sue stepped atop her seat, as lithe and loose as a ballet dancer just
finished with her warmup. Captain of the ship, she had just gotten the four
of us wedged tight into our corners of the rubber raft. (I couldnt help but
compare her casual manner upon arising with that of a commuter getting up
to leave a bus at the next stop. Then I remembered that she was the driver.)
She was, I supposed, not planning to abandon us but merely standing up to
get a better view down into the boiling white water of the rapid, toward
which we were drifting with the current. Sue guided us by an occasional
stroke on the oars.

The water of the Colorado River was deceptively calm  the way it
always is, upstream from waterfalls. Like a reservoir above a dam. But, I
reassured myself, Badger Rapid is not yet a waterfall. One must be
quantitative about waterfalls, after all  Badger rates a mere 7 on the Grand
Canyons scale (10 is a barely navigable monster rapid; I suppose that 11
would therefore rate as a waterfall). Beyond the lip of the rapid, where the
flat river seemed simply to end, great eruptions of white water were being
thrown into the air, as if the rapid were advertising its virility, like a gorilla
thumping its chest.

Strangely, each great splash was soundless  drowned out, I supposed,
by the sustained roar of the rest of the rapid. The splashes were just white
flashes against the reddish-brown background of the Canyon walls, first
here, then there. Like lightning when youre too far away to hear the
thunder. But those splashes are, ahem, close. And getting closer. Were we
going through that?

As we drifted toward the rapid, Sue gave us a quick safety lecture.
Life-jackets are very nice when you need them, but the major goal is to keep
yourself inside the boat. "Crouch down in one corner of your
compartment," she said. "As the floor of the boat rises and falls with the
waves, pump your legs, just as if you were skiing. Wedge yourself into a
corner, and keep your feet under your body. And keep a secure grip on
your two handholds. Always two."

Her lecture completed, Sue sat back down again just as causally as she
had stood up, routinely fastened her lifejacket a little tighter, and checked
her belt knife ("Dont get entangled with a rope if we flip over," shed said
only minutes before). She pushed on one oar and then the other, rowing us
over to the exact spot where she wanted to enter the rapid, never taking her
eyes away from the white water ahead. I think she likes running rapids.

THE WATER WAS SO CALM that we felt a bit silly, wedged into our
corners and hanging on with whitened knuckles. Then we slid over the
smooth lip of the rapid and into the first gentle, rolling wave of the tongue.
Pleasant, but Im not fooled. When we finally reached the tip of the tongue,
a viciously cold lateral wave splashed over the right side of the boat, eliciting
yells from those slapped by it. Even when one expects it, a bucket of cold
water is still a bucket of cold water. After that brief introduction, everything
happened so quickly that we had no time to think about what we were
doing.

The boat bent up in the middle as its bow climbed a wave, exhibiting
a flexibility that we hadnt suspected. Over the crest of the wave and the
boat arched its back just as radically the other way. A rubber roller-coaster.
Aided by several swift strokes on the oars, Sue slid us sideways around
another standing wave that ended in a boiling white "hole." We had
successfully cleared the hole when still another small wave appeared out of
nowhere and threw several buckets worth of cold river over the stern
compartment. Two more big waves followed. Everyone was yelling,
involuntarily or with perverse pleasure.

The river spun us around, sending us careening downriver stern first.
The rubber floor of the boat seemed to have a life of its own, dropping slack
and then popping up into the compartment with some force. As if we were
skiing an endless field of moguls, our legs pumped like pistons, keeping us
wedged into our chosen corners.

Then the twisting and turning was over, the ups and downs gradually
moderated, and we were left with just the cold water dripping off our
amazed faces. We saw a swirling back-eddy alongside, where the water was
gracefully sweeping back upriver. Pulling hard against the currents, Sue
rowed us over into the eddy  whereupon we reversed course and were
carried back upriver.

What is she up to now? Is she going to run it again? Not that
we had any time to marvel at all this. Per instructions, we were all bent
over, bailing buckets of water out of the bilges. We scarcely managed to see
the incredible Marble Canyon scenery for a few minutes.

Take care to get what you like or you will be forced to like what you get.
Where there is no ventilation, fresh air is declared unwholesome.
GEORGE BERNARD SHAW

SUE SAID that she normally stayed out of the back eddies, but that we had
to provide emergency towing and pickup services for the other boats in case
they got into trouble. (Ah, but who covered us?) Which was one reason
why we had to bail the water out of the bilges as soon as possible. A boat
thats overloaded with water is no fun to row and doesnt make a particularly
swift rescue vehicle. Hint, hint. So we tried to get the last teaspoon of river
out of the bilges. Sue runs a tight ship.

From our new vantage point, we got to watch the other six boats come
through. We could barely hear their passengers yelling above the roar of the
rapid. A boat would disappear into a trough and then surprise us by
suddenly reappearing, on a different side of a wave than we had expected.
Most boats got a lot wetter than we did. The last boat through hit a wave
wrong, briefly lost control, and slid down into a fury of boiling waves.
When it finally sped past us, looking somewhat low in the water, all four
passengers were bailing furiously. Sue pulled us out of the back-eddy with
a series of strong strokes and we finally caught the main current to follow
them down the river.

Susan Bassett, our boatman and an ex-Harvard Medical School
secretary, is called "Subie" by the other boatmen. She is tall and slender,
with large expressive eyes that dont miss a thing. As we were renewing our
acquaintance, I remembered the first river trip I took with her, down the
Middle Fork of the Salmon River up in Idaho. At the time she wore a
baseball cap with the letters "SUE B." on the front (the first river
crew on which she rowed had another Sue). I suspect that the cap is long
since deceased, but everyone still calls her Subie. I took my first big course
on brains at Harvard Med when she worked in the Deans Office there, and
I strongly suspect that she was the helpful secretary who somehow found a
spare microscope for me to borrow. We meet again in the strangest places.

AN ESCALATOR FOR BIRDS? It certainly looks like it. Some of the
birds are circling around over above the left bank, rising higher and higher
on each revolution. Dan Richard spotted it, that being one way that glider
pilots spot thermals  just look for the birds utilizing them.

Abby, upon seeing this, told us about what shed seen yesterday down
at an ancient cliff-dwelling, Betatakin. "We got down in this canyon with
the park ranger about nine in the morning, just when the sun was starting to
illuminate the cliff-dwellings set back in this enormous alcove in the cliffs.
But out in front of Betatakin, circling in the air, must have been three dozen
big birds. Probably turkey vultures."

"They were riding a thermal up out of the canyon?", asked Dan
Richard.

Abby nodded. "Thats what the ranger said. They just started circling
lazily, and soon they were halfway up. A little longer, and they were up out
of the canyon. Then they started flapping away with that distance-covering
wingbeat of theirs. Pretty soon they were out of sight. By the time wed
hiked further down the canyon to the ruins, they were all up the escalator
and gone. Off to work."

Hot air rises. And birds know it. Or at least the birds that can discover
it are a lot more efficient, get more babies to grow up, and so populate the
world with smarter birds.

Everything is what it is because it got that way.
the biologist DARCY THOMPSON,On Growth and
Form, 1917

THE ARGUMENT FOR A GRAND DESIGN usually says something to
the effect that fancy anatomy is too sophisticated to have arisen by chance,
that it goes against common sense to say otherwise. Architecture requires
an architect, and so forth.

The argument against design usually substitutes Darwinian natural
selection, saying that all our abilities have been shaped by gradual
adaptations, such as the loose skin that gliding snakes use. In this
adaptationist view, success in one endeavor allows the genes that promote
success to produce a relatively larger share of the next generation. Even
small differences in survival and reproduction count when compound interest
operates over thousands of generations. And so Darwins finches arise, a
whole family of birds, each specialized for a particular food or two. What
can happen in a newly colonized island in only a few millennia may take
longer to happen back on the mainland, but the basic process is the same.
Its probably how all species have arisen, including us.

Abby was not convinced by this approach to evolution. "You know,
what bothers me about this standard evolutionary story are not the usual
things, like the eye  how could such a perfect optical instrument arise by
chance, surely it bespeaks the guiding hand of a Creator  because I buy
adaptation for useful traits." She took off her big straw hat and brushed
back her blond hair. "But there are just too many things around in which
our talents seem greatly in excess of anything our environment demands."

She leaned forward, then continued with a sweeping gesture. "Take
music, for example. What on earth is the survival advantage of being able
to follow, let alone compose, Bachs Goldberg Variations? Sure, a
little love of music might have helped social cohesion, a little dancing to
music might have eased social tensions. But I dont believe for a minute that
prehuman primates held rock concerts and that this made them better
warriors or more peaceful citizens. And even if they did, how did it select
for the fancy musical abilities like harmony? Four-part inventions?
Adaptation arguments just wont work for music."

No, we conceded. Try as we could, we couldnt think of any reason
that our considerable musical abilities  far in excess of the frenzied
chimpanzee rain dance  could have aided evolution enough to help a
prehuman survive better.

But, we pointed out, some things in evolution are sidesteps in which an
anatomical feature turns out to have additional, unexpected uses besides the
one for which natural selection shaped it. Maybe music is another sidestep.

"So what was the original talent from which music emerged?", asked
Abby, pursuing her point.

A good question. "Maybe language? They are both timed sequences
of sounds," answered someone I didnt know. I liked that answer.

"But dont abilities such as music," continued Abby, "make you wonder
if there isnt some higher principle shaping life, some goal to evolution?"

No, we biologists replied. Thats not to say were sure there isnt, but
our agnosticism is an occupational hazard of our profession. We cannot
assume the existence of a guiding principle because it would discourage us
from seeking simpler explanations. It would paint us into a corner. Well
just have to see if we can come up with a scenario for the invention of music
via a sidestep from some adaptive improvement in another skill.

"And what about laughter, what is its evolutionary utility?", Abby
added. Here we go. "The chimps and monkeys may romp and tickle, but
they dont laugh or seem to have a real sense of humor. And laughter is
almost an involuntary reflex, not what you expect for higher cerebral
activity. So where did natural selection produce that?"

Sigh. Ill add it to the list. Explanations needed: Music, humor, and
now laughter. We have a whole two weeks in which to think about them.

Subie calls our attention to Ten Mile Rock, a big pillar of rock on the
right bank, a few stories high. Once upon a time, it fell off the face of the
cliff above. Somehow it didnt topple over upon crashing into the river
bank. Not your usual balancing rock, like the one we saw driving up the
road from Navajo Bridge to Lees Ferry. Those are formed by erosion,
eating away a softer layer that underlies harder stuff.

I liked the way several people responded to Abbys point about the
involvement of "something else" in evolution. They said that doing science
is rather like piecing together a jigsaw puzzle, trying to make the big picture
emerge from all the little fragments.

So far, the big picture looks like a tree. A single big tree, not a lot of
little ones.

Just as there were no birds before 200 million years ago, so there were
no large-brained primates until the last several million years. We dont know
if the prehuman fossils we find are direct ancestors of ours or just cousins
on a slightly different branch of the tree. But the shape of the rest of the
underlying tree is abundantly clear to anyone who examines the facts. And
it isnt a collection of independent creations every now and then.

Were apes. Apes come off the primate branch. Primates are rooted
in the mammals. The mammals and the birds evolved from the reptiles.
About the time that the canyon surrounding us was laid down, the reptiles
evolved from amphibians. Earlier, the amphibians evolved from fish, which
evolved from primitive chordates, which evolved from an invertebrate rather
like the sea-squirt. The invertebrates, and all other multicelled organisms,
evolved from a single cell type called a eukaryote  or, as I call it, Supercell.
Supercells are the main trunk of the evolutionary tree, the one from which
several dozen major branches have arisen.

Supercell took a long time to evolve from Simple-cell, the bacterium.
Bacteria have been around for about 75 percent of the Earths existence,
three times as long as Supercell. In fact, Supercells constituents such as
mitochondria look as if they may have been hitchhikers, independently living
organisms that were taken in and put to work. Supercell looks to be a great
committee effort, self-organized from bacterial components, coevolving
together. The bacterium in its many forms evolved from some ancestor,
probably the outcome of some competition in the early oceans between
various forms of self-replicating chemical systems using a common genetic
code. The bacteriums machinery for making proteins will even construct
human proteins  such as the growth hormone that dwarfs lack  if you snip
the genetic instructions for making these proteins out of the DNA of a
human cell and insert them into the bacterium, thus neatly demonstrating
that we still use the same protein-building system that was around during the
Earths childhood.

We can even imagine how chemicals floating around in shallow waters
self-organized themselves during the Earths infancy into primitive bacterial
cells that had the amazing ability to make copies of themselves. We can
guess how the genetic coding instructions might have evolved, those
necklace-like blueprints that tell the cell how to construct another living cell.
We know how the carbon-based chemicals that make up living organisms
can have arisen before life itself, since we can see them being synthesized in
many different laboratory experiments mimicking the conditions that existed
on the early Earth. And how carbon and all the other elements heavier than
hydrogen and helium were constructed in the dense centers of collapsing
stars. And something of how the Big Bang evolved from pure energy to
form stars of hydrogen and helium.

The whole chain of events has taken about 15,000-million years, while
our peculiarly large brains have only evolved in the last 2 million years. The
puzzle has been pieced together, largely by the last few generations of
humans, using science to build on the cultural edifice of many thousands of
generations. There is no need to postulate a miracle at any stage. Its just
like doing a jigsaw puzzle: whenever you think that there is no piece that
will can possibly fill a blank space, you dont just throw up your hands and
insist that only a miracle will solve the problem. You keep looking, and
eventually you find something that links together the parts of the puzzle.

Yet the magnificent façade of science is not a completed jigsaw
puzzle, not now. Perhaps there will someday be a piece that wont fit, a
space that wont fill. Still, the critics who now and then cry "unproved"
(rather than "unfinished") are shortsighted if they cannot tell that the picture
contained in the incomplete puzzle is a single giant tree. One need not have
lines connecting every generation with the immediately preceding one to see
that the big picture is one big tree, and not a forest of little trees
independently created de novo every now and then.

The theory of evolution isnt like a Euclidian theorem describing
geometry that must be "proven"  its a historical synthesis that explains
major features of the past in an economical way, a way that makes correct
predictions. Its a well-tested theory that ties together the entire edifice of
biology, from molecules to humans. But its not complete yet, and its
implications arent always clear.

[Miracles rest simply] upon our perceptions being made finer, so that for a
moment our eyes can see and our ears hear what there is about us
always.WILLA CATHER, Death Comes to the Archbishop,
1958

SOAP CREEK RAPID has come and gone. Were still wet, though the
water is now out of the bilges. Soap Creeks rated a 5, though some people
have gotten into real trouble here. Subie points out an inscription, carved
into a rock in 1889, telling of the death of F.M. Brown  and Peter
Hansbrough, who carved it, was himself drowned five days later. While
fatalities do occur on the Colorado, theyre pretty rare these days due to
better boats and better boatmen, thanks to a century of experience passed
on from one generation of river-runners to the next. For example, now one
rows rapids facing into them, rather than backwards in the traditional
rowboat style. Funny how it helps to look where youre going. Such
improvements make cultural evolution work a lot faster than biological
evolution  which might have to wait for a variant that did things
backwards.

Lacking foresight, evolution is simply opportunistic, retaining those
features that were available when opportunity knocked, forming a
patchwork of makeshifts. We too are imperfect, products of the unique set
of challenges posed during the ice ages after our ancestors got started with
a brain the size of a gorillas. Somehow, evolution enlarged that brain
threefold and created a unique set of inborn skills for making tools, throwing
spears, and speaking sentences. It even created the capacity for music and
poetry. And humor. Somehow.

We are all sitting at a cosmic poker game in which the house has an infinite
supply of chips. Neither we nor our genes can ever really win, since we can
never cash in our chips and go home.... There is nothing but the game, and
since it has been going on for a long time, only the best players are left. It
is an existential game, the only one in town, and all we can do is to stay in
as long as possible. We are all playing, so perhaps we may as well enjoy it.
Certainly we should understand it.
the sociobiologist DAVID BARASH, The Whisperings
Within, 1979

ANCIENT REPTILE TRACKS are to be found over on the left bank
somewhere, but we dont have time to stop. Besides, were busy bailing
again. Sheer Wall Rapid only drops the river level down a story or less, but
we just happened to get a big wave over the stern, right where I am sitting.
An old guidebook says that Sheer Wall is rated a 7, but the blue bible
indicates that modern boatmen only rate it a 2. Sic transit gloria.

The reptile tracks are in the Coconino sandstone, the
Sahara-Desert-like layer that emerged from the river back about where the
bridge span the canyon. Here, its high above the waterline now. Curiously,
no reptile fossils have been found in it, just tracks. I was going to say that
maybe the vultures and hawks ate them all, but the only flying animals back
270 million years ago were the insects. The river certainly does focus us on
time, immense stretches of time.

Mile 17 House Rock Rapid

THE RIVER HAD BEEN GETTING SLOWER. And wider. Subie was
having to row more. And then there was the sound of an airplane roaring
somewhere  except that it didnt disappear into the distance as airplane
sounds are wont to do. It just slowly got louder. Subie smiled at our
attempts to locate the airplane and said that House Rock was just around the
corner. House Rock Rapid, an 8, is an even larger fraction of a waterfall
than Badger.

About the time that we started to worry about our cameras getting
soaked, Subie told us not to bother stowing them away in our ammo cans
yet, because we were first stopping above House Rock Rapid to have a look
at the rapid from shore. She beached our boat on a broad sandy beach on
the right shore, and we all climbed out.

Subie and the other boatmen all went bounding through the field of
boulders to their favorite lookout place. The rest of us, still clad in orange
lifejackets, wandered down the beach to it up close. For most of a city
block, the river was a series of big waves. There were a few giant crests but
mostly smooth ups and downs, many as tall as a person. Here and there,
great holes of white water could be seen where the river poured over a steep
rock face in the manner of a waterfall, carrying a lot of air underwater with
it; this plunging turbulence is what the boatmen call a "hole."

But the big waves stood still, like hills and valleys usually do. Even
those of us who understood why found this amazing. In the ocean, waves
move forward but the water doesnt  the energy is just transferred forward,
as in a tightly-packed row of billiard balls hitting one another
wham-wham-wham, with only the last ball in line actually moving very far.
In a rapid, waves are stationary but the water moves. Standing waves,
literally, just like Pythagoras discovered 2500 years ago when analyzing
musical chords. They do splash around a little, not being completely
stationary, just to make things more interesting for the boatmen. And, of
course, the amount of water coming down the river makes a big difference
in where the waves and holes are located in the rapid.

Unfortunately the water level of the Colorado is now under the control
of technicians at the Glen Canyon Dam, Dan Richard explains. And not just
seasonally  since about 1980, they have adjusted the water release every
hour according to how many air-conditioners are turned on in Los Angeles
and Phoenix, engaging in what is called peaking power generation. Without
so much as an environmental impact statement (which the government was
legally required to file, according to our lawyer), the Colorado is now
flooded daily with large artificial tides, rising and falling with the business
day. Release twice as much water several hours later and the standing
waves are drowned by high water. To the people who built and run the
dam, the Canyon is an inconsequential sluiceway. And all those beautiful
canyons upriver of Glen Canyon Dam, with names like Music Temple and
Tapestry Wall, are now illuminated only by a pale green light. And the
reddish brown silt, which for millions of years gave the river its rich color,
is now filling the drowned canyons. This is not your usual benign
flood-control dam. High-rise hydroelectric dams dont prevent floods so
much as they create them.

THE BOATMEN were in a hurry and waved us all back to the boats in
short order. We wanted to get started before the rush of water arrived, from
when the air-conditioners were turned on this morning.

Subies boat was again to be the first to take on the rapid, and she
rowed upriver with a strong backstroke to position our boat in the center of
the river channel. She again specified exactly which handholds were safe
and which were to be avoided. "Dont grab the blue line around the outside
of the boat, unless youre swimming for some reason and need something to
grab. And you dont want to get wrapped up with a rope, or get your leg
wedged in a crack. If the boat flips over, you want to be thrown
clear and not trapped underneath." In the life jacket, Subie explains, "youll
go bobbing down the river just like an orange cork, getting a unique
corks-eye view of the white water. And someonell row over and pick you
up." Reassured, we faced the rapid  visible now only as a lot of splashing
water beyond the smooth surface of our backed-up lake.

"Oh yes," Subie added, "if I yell HIGH-SIDE, I want you to throw
your weight to the high side of the boat. Thats in case one side of the boat
gets submerged in a wave." Just as in sailboats, one high-sides to
counterbalance. In a hurry.

Subie, complaining earlier about someone tracking sand into the
bottom of the boat, had said "Oh, well, were taking her to the boat wash."
Running House Rock Rapid was indeed like being in a washing machine,
first a wave from one direction, then from another, overlapping the first.
Again and again, as if giants were shuffling a deck of watery cards. And
when we bailed the boat, out went the sand too.

We got cooled off again. The water temperature is cold, about
9° Celsius (also known as about 48° Fahrenheit in certain
insular parts of the world, namely Yemen and the United States, most
everyone else having officially gone metric). The river water doesnt come
from the surface of Lake Powell, the dam intakes being well below the
surface to avoid sucking in all the floating trash from the boaters, and the
suns rays dont warm up the water very much down at those depths.

BACK TO THE BIRDS. We know they evolved from the reptiles but, aside
from a half-dozen specimens of a small dinosaur called
Archaeopteryx whose forelimbs suggest wings, the intermediate
species have not been identified very well. The key evolutionary problem
with birds, however, has been in figuring out how they got started on their
flying careers. Standard reasoning, based on Darwins natural selection,
usually leads people to think in terms of "adaptation"  that each successful
little stage of anatomical change is rewarded with more descendants in the
continuing battle for the survival of the fittest. And if the next stage proves
still more useful, it is further rewarded, and so on.

Feathers are all very nice for flight, but one needs a lot of them before
they do any good at all. A few feathers on the limbs of a running dinosaur
would hardly induce liftoff, to recall Stephen Jay Goulds lovely phrase. So
how did the reptile develop ever greater numbers of feathers, to build up to
the threshold for flight? Evolution has no foresight, in the manner of human
consciousness  it cannot just plan ahead for something useful in the future,
such as when the unexplained "#" and "*" buttons were included in
pushbutton telephones decades ago, anticipating the future expansion of
special services (and causing millions of parents to have to admit, when
inevitably asked "Whats that for?", that they didnt know).

Even if we knew that there was another ice age coming, we couldnt
prepare for it by growing more and more body hair with each generation
until we became hairy again. Evolution selects useful features, but based on
present-day needs. If you dont have them when theyre needed 
well, its just someone elses turn.

Which, of course, suggests that feathers were initially useful for
something besides flying. Indeed, feathers are useful for the same reason as
body hair: thermal insulation against the cold. Im sure that someday we
will discover a feathered dinosaur; maybe well get lucky while out searching
for the footprints of running dinosaurs, and find a place where one of them
stumbled and fell. If it left a nice imprint in a hardening mud flat, it might
reveal an abundant plumage on an otherwise reptilian body.

The archaeologists studying the prehuman footprints found at Laetoli
in Tanzania, where hardening volcanic ash preserved the footprints left by
some upright-walking hominids 3.7 million years ago, presumably have the
same hope: to find where someone slipped and fell, or sat and rested. Then
we could see how much body hair they had, whether they were wearing
clothing or perhaps carrying a basket, and the like. The record of the past
is terribly biased by the fact that hard evidence (literally hard: bones, stone
tools, pottery fragments) survives better than wooden spears, carrying
baskets, and characteristic behaviors. Yet the soft evidence would, in the
case of humans, tell much more of the story.

BOULDER NARROWS, this spot is called. It is narrow enough to make
this the deepest place on the river for the next 110 miles. And there is a big
slab of limestone sitting in the middle of the river, forcing the boats to detour
one way or the other.

There is some driftwood atop the boulder, left there by the great flood
of 1957, one of the last big spring runoffs before the dam was built. Since
the dam gates were closed in 1963, most of the driftwood has been trapped
in Lake Powell. River parties dont collect driftwood anymore for bonfires,
since what is left is the home of birds and rodents.

FEATHERS MIGHT HAVE AIDED THE SURVIVAL, in temperate
climates, of those who had them, keeping those feathered few somewhat
warmer during cold nights and colder winters. And the more feathers the
better  provided that the dinosaurs had a good way of cooling off when
they needed to. But, of course, all they needed to do to control their blood
temperature was allow some extra blood to circulate through the feathers
while moving, like water through an automobiles radiator. A nice system,
and we can surmise that natural selection suitably rewarded the genes that
inadvertently invented it.

Nature, of course, is always trying out variations on a good thing. The
variants that find a use  such as downy insulation  are likely to be retained
by Darwinian natural selection. But someday, such as when there were
enough wing feathers, they might become useful for something else  say,
for gliding quickly down a hill while chasing prey. Or for jumping up into
the air to bat down a passing insect. From such mundane beginnings may
have come the graceful flight of birds.

Evolution rarely proceeds in a straight line from A to B, probably
because there are no goals to evolution. Evolution is always finding new
uses for old things; this innovative use is the primary basis for how animals
have become smarter and more versatile. Bootstrapping can happen when
we least expect it, a new combination of anatomy and behavioral skills
suddenly exhibiting unexpected properties that allow for a quantum leap in
capabilities. Was this the route for the invention for music? And laughter?
But as a sidestep from what...?

Evolutions tempo is a lot like the rivers course through the Grand
Canyon. There are long, quiet stretches of flat water where nothing much
changes. Then there are exciting periods of great turbulence, such as House
Rock Rapid, which are followed by an intermediate stretch where currents
swirl around, finding a new dynamic equilibrium, becoming quiet again.
Most animal species dont change much for millions of years. When they do
change, it is during one of those turbulent periods, when they are tested,
when they sink or swim. What emerges is sometimes a new species,
retaining those features which were handy. The evolutionary theorists think
of this scenario as a punctuated equilibrium. Myself, I think of it as
being like my favorite river: the Colorado River going down the Grand
Canyon Staircase.

THESE BOATS DONT SINK EASILY. I just saw a boat, being rowed
temporarily by an energetic passenger, impale itself on a rock hidden just
below the surface of the river. Such rocks are easy to avoid, since the
swirling waters nearby give them away, but the boatman wasnt supervising
carefully on such an easy-looking stretch of river. Abby saw the boat about
to run over the hidden rock and yelled "Feet up!" loudly. The two
passengers in the front lifted their feet quickly as they saw the rubber floor
of the boat rising up, and the boat began to slowly pivot around this point,
carried around by the river currents. Then it slid free of the obstruction
uneventfully, or so it seemed.

Later, when no amount of bailing could reduce the foot-deep
bilgewater, the boatman leaned far over the bow and felt underneath of the
boat. He came up muttering "Yep, big triangular hole." Pivoting atop a
sharp rock works just like a drill. Its just a hole in the floor; the boat wont
sink (unlike a rowboat, the flotation comes from the air-filled
compartments). At least the front pontoons were spared. There are, in any
event, close to a dozen separate compartments for air, and its pretty hard to
hole more than two at a time. A nice design.

The boatman decided that repairs could wait until we made camp.
That boat took a lot more rowing than the rest, hauling along all that water
in the bilges. Penance. One passenger was transferred to our boat to lighten
the load. So, though we survived Badger and House Rock, the only damage
was done by a minor rock in a quiet stretch of river.

EMERGENT PRINCIPLES are things not predicted by a reductionist
taking-things-apart approach  things where the whole really does turn out
to be different than the sum of the parts. Not just greater, but often
qualitatively different  such as bird flight, emerging willy-nilly from enough
thermal underwear.

Most nonscientists dont know very many examples of emergence,
other than snowflake crystals. And most scientists know only several
examples within their own specialty. Without analogies, it is indeed hard to
imagine us humans happening without design  and so one is led to suspect
some sort of cosmic principle, if not the guiding hand of a Creator, shaping
evolution towards complexity.

Evolutionary theorists usually have seen enough examples of
emergence to have faith that, as in the case of natural selection shaping the
eye, adaptation and emergent "sidestepping" will be sufficient to explain the
overall trend of evolution toward intelligent animals. Including ourselves.
But as I said before, we cant be insistent about this expectation in the same
way as when we relate the fact of evolution itself  our working hypothesis
about emergence is, for us, an occupational hazard of being researchers.

Mile 21 North Canyon
First Campsite

PATCHING THE BOAT turned out to be easier than I thought. But then
I had imagined a surgical sewing job of whale-sized proportions. I had
forgotten about the nautical equivalent of duct tape. The simple repair
procedure? First unpack the boat and remove the tubular frame. Then tilt
the boat up on one side, propping it up on the beach in a near-vertical
position, using an oar or two stuck in the sand. Next, just as when patching
an inner tube, rough up the surface around the tear in the floor. These boats
carry a repair kit that consists primarily of odd-sized sheets of neoprene,
some sandpaper, and a can of contact cement. I pushed on the inside while
Alan smeared on some cement and applied a patch from the outside. Then
we traded places and he applied another patch to the inside. And except for
repacking, which Alan is saving until morning, that was it  a whole lot
easier than fixing a tire. I can see that this is my kind of boat.

As we were resting in camp after our long days labors, sampling the
contents of the little aluminum cans kept cool in the bilges, the wind came
up. The sky clouded over and then it really began to blow. The fine
particles of sand (this stuff is sometimes called "blowsand" for just this
reason) began to billow in great clouds across the camp and out over the
river. There were sand dunes forming before our very eyes, but we were not
inclined to watch as the fine sand kept getting into our eyes. Bandanas came
out and were draped around the edges of sunglasses, hats were held to
shelter faces from the wind, and we all headed uphill. The easterly wind was
blowing down out of the side canyon, so we all gathered on the upriver
ledges of Supai around the corner, huddled against the force of the sand
gusts. Still we were sandblasted. Sandstorms, it is said, do not last forever.
Mike Marsteller, one of the other boatmen, said it was one of the two or
three worst sandstorms hed ever experienced in 500 days in the Canyon.

THE SUPAI LAYERS in which we took refuge vary enormously, probably
because the climate changed more frequently in some periods of the Earths
history and gave rise to thinner layers than those deposited during longer
periods. Near camp, we found thin layers of Supai sandstone. Ten stories
up, another ten stories of steep cliff begins with thicker layers of more recent
Supai. Then atop that is the crumbly Hermit shale forming a 45x slope,
topped by the cliff-like Coconino and Toroweap sandstones and the Kaibab
limestones. Cliff-forming means hard stuff.

Five layers have arisen around us in only 21 miles of river, and we hear
that the Redwall Limestone will start just downriver from here. We also
hear the next section of river is named "The Roaring Twenties" and that we
should wear our raingear tomorrow morning if we dont want to get a little
cold. There are nine rapids in ten miles.

Cold, with it this hot? But when I go to wash the sand and grime off
in the river, I am reminded that the river is beer temperature. My wet
bandana comes away from my face coated with fine sand particles; it feels
good to get the sand off. I even get a nap before dinner.

SITTING ALONG the river after dinner, the storm having disappeared, we
heard the clanking sound of breaking and falling rock.

The boatmen all started exuberantly to jump and shout, running around
trying to get a better view of the rockfall. In all their years in the canyon,
some had never witnessed an actual spontaneous incident in the continuing
erosion of the Grand Canyon. They cheered on the rocks when they
tumbled into sight across the river. And plunged in, with big splashes:
"Ker-plunk, ker-plunk." We watched the final trickle of small rocks, trailing
along behind the big rocks, with a feeling that we might never see it again.
Few of the millions of visitors to the Grand Canyon each year ever get to see
it as anything other than a static colossus  a frozen, finished sculpture.
Now we, at least, know better.

Erosion made the Grand Canyon. Rocks falling downhill, shattering
into smaller rocks along the way, is the most obvious aspect of erosion.
What goes up (via lava upwelling and the mountain-building uplifts that
occur as sea-floor spreading causes continental plates to come together and
push their colliding edges into the sky) must eventually come down. Aiding
gravity in this matter are water, wind, and ice. For example, the water that
gets into cracks in rocks at higher elevations is likely to freeze in winter,
forcing the halves of the rock further apart just as surely as a wedge splits
firewood. So watch out in the springtime for a lot of fresh rockfalls.

Then, a half hour after the rockfall, we got another surprise  the river
changed color! Chameleons, maybe, but a river? Starting in the middle of
the channel, a dark red tongue intruded into the otherwise mint green waters
of the Colorado. Then the tongue widened as we watched, soon filling most
of the river except for the shallows along the shoreline. (Why a tongue?
Water flows faster in midriver because the shorelines slow down the flow.)

Evidently that sandstorm was a side effect of a big rainstorm up north.
This red color is, Subie tells us, what the Colorado River used to look like
most of the time, before the dam created that big silt trap called Lake
Powell. Now the Colorado turns red only when a side canyon floods
somewhere within the park. But where? The Paria doesnt run red, Subie
points out, so the water was probably dumped into Soap Creek, Tanner
Wash (which created Sheer Wall Rapid), or Rider Canyon (which donated
House Rock Rapid), those being the only possible sources of so much red
silt. So, thanks to this little bit of detective reasoning, we know that we
missed seeing a flash flood in a side canyon by only about a dozen miles or
less.

There seem to be no end of unusual events today. At this rate, well
see a comet or a supernova tonight.

I ALWAYS SLEEP BADLY the first night out, and so after tossing and
turning in my sleeping bag for half an hour, I finally got up and made my
way back down to the river where a few people remained, talking quietly.
The skies had cleared and I could actually see my way by starlight and a bit
of moonlight reflected from the far canyon wall.

Like many others, I had been somewhat skeptical about the boatmens
plea to avoid the use of flashlights on aesthetic grounds (light spots flashing
across the canyon walls, as someone turns around, seem inevitable no matter
how carefully one tries to restrict a flashlight beam to the path). We thought
wed stumble around our dark camp bumping into rocks and trees. But it
actually works, I could see the whole camp; if Id used a flashlight, Id have
seen only the swath cut by the beam. I also would have lost my
dark-adaptation and so would have had difficulty spotting the fainter stars
for the next half hour. They were indeed hard to spot, what with the moon
shining from behind the western canyon wall. Being at the bottom of a
narrow canyon, we see only a narrow swath of sky. It rather focuses the
attention.

As I looked up at the sky for clusters of familiar stars, I knew that I
was a real amateur compared to our ancestors who carefully studied the
night sky. The names of many constellations, such as the Big Bear (latinized
as Ursa Major), have come down to us from the time before writing was
invented 5,000 years ago. Our ancestors had a good mental image of a bear,
and they could fit seven stars to it.

However, they had a rather limited mental image of their family tree 
restricted to several generations, mostly people theyd seen sometime in their
lives. Passing on information for which there is no reminder in the
environment, such as a real bear, is not easy (which is the reason why most
of us cant name our eight great-grandparents, either  and why the Navajo
forgot the Yukon). A skill, cultural artifact, or ritual helps carry information
along through the generations, but only with the inevitable modifications that
eventually change things radically after a dozen generations. As culture
changed, the constellation Ursa Major came to be called the "Big Dipper"
in some parts of the world, and to anyone who has used a ladle, its hard to
see a bear there anymore. Most of us, alas, see more punchbowl ladles than
bears.

Living in a city, one seldom sees the stars at all. That leads to a certain
insular perspective: at night in the Canyon, I realize that Im sitting on a
planet, almost feeling it turning as I see new stars suddenly appear from
behind the high canyon wall on the east side of the river. Here we dont have
to struggle to see through all that distorting haze near the horizon; instead,
the stars pop out when we study the top of a cliff. The Milky Way spans the
top of the canyon walls. Our very own galaxy, seen edge-on. A
few-hundred-billion stars, plus our Sun. Plus the black holes and dark
matter of sundry sorts. We passed around the birdwatching binoculars in the
starlight.

NOT ALL "STARS" are sharp points of light; some are rather fuzzy. And
it isnt just poor optics, as an adjacent star may appear quite sharp. The
German philosopher Immanuel Kant, back 200 years ago, correctly
interpreted the fuzzy stars as "island universes" of millions of stars well
beyond the confines of our own galaxy, the Milky Way. Today we use the
word "universe" to include all galaxies, just as we have expanded the
definition of the word "galaxy" beyond its original Greek meaning of "milky
way."

There are two galaxies that circle our own Milky Way, rather like the
moon orbiting the Earth. They are close enough to appear too large to be
passed off as mere fuzzy stars. From the southern hemisphere, they appear
as luminous clouds to the naked eye. The sixteenth-century Spanish
explorer Ferninand Magellan was the first to tell Europe of these great fuzzy
patches of light and they have been known there as the Magellanic Clouds
ever since. There are actually about 20 galaxies in our part of space, known
as the Local Group (which is 3 million light years in diameter). Then for
almost 50 million light years, space is virtually empty  before arriving at a
particularly rich collection of about a thousand galaxies known as the Virgo
Cluster. And there are lots more galaxies than just those.

All those galaxies are still fleeing the Big Bang, that cosmic point of
origin that marked the beginning of the universe as we know it. The Big
Bang occurred 12,000- to 17,000-million years ago. Call it 15 billion years
ago for the sake of convenience (at least until they recalibrate the Hubble
constant again, that great astrophysical fudge factor that relates redshift to
distance).

The world began with what it is now the fashion to call the "Big Bang"... it
could not, of course, have been a bang of any sort, with no atmosphere to
conduct waves of sound, and no ears. It was something else, occurring in
the most absolute silence we can imagine. It was the Great Light.
LEWIS THOMAS, Late Night Thoughts on Listening to
Mahlers Ninth Symphony, 1983

IN THE BEGINNING, there was no matter. Everything was radiation 
the stuff that constitutes light and radio waves alike. Radiation comes in
packets called photons: radio waves, infrared and ultraviolet light, and
X-rays and gamma rays, theyre all photons just as red light is. The only
difference is the amount of energy stored in the packet: lots in X-rays but
not so much in infrared photons. Red photons are your average sort of
photon  around here, during the day.

Out of such packets of radiation, matter was created (just remember
E equals mc2, which tells how energy and mass are
interconvertible). Two photons of light colliding in the dense packing of the
early universe (another way of saying it was very hot) can produce protons
and neutrons. In the first microsecond of the lifetime of the universe
(one-millionth of a second), it was simply too hot for anything else to exist
for long. Particles were converted back into photons almost as fast as
photons were converted into particles. But by the time that a millisecond
(one-thousandth of a second) had gone by, the universe had expanded and
cooled enough for lighter-weight elementary particles, such as electrons, to
form from light and survive.

Actually, the story should be told in terms of quarks, the building
blocks of protons, neutrons, electrons and, in fact, everything in the
universe. Quark? When the physicist Murray Gell-Mann postulated these
building blocks in 1960, he wanted a neutral term to describe them, with no
physical connotations  and so he picked a made-up word from that
masterpiece of make-believe, Finnigans Wake. It has been noted by
literary killjoys that James Joyce was living in German-speaking Zurich at
the time he wrote about quarks. And quark, in German, means "cottage
cheese." But thats not a bad analogy: the "quark soup" of the earliest
moments of the universe may be conveniently envisaged as slightly lumpy.
Mostly light, but with little bits of matter forming within it.

With more expansion and a thinner "soup," photons quit colliding with
each other except on rare occasions. And the particles in the infant universe
began to cluster together long enough to assume new identities. Between
three minutes and a million years of age, the universes elementary particles
began to form clusters as the electrical attractions between positive protons
and negative electrons brought them together. When an electron and a
proton stick very close together, the combination is called a neutron. Or an
electron might begin to circle a proton at a great distance; this particular
combination is called an atom of hydrogen. This looser clustering was an
important event because the neutral hydrogen atom is less likely to capture
passing photons than a separate electron and a separate proton.

At approximately 3,000° K. (thats about as hot as a lightbulb
filament), as much matter is converted into photons as photons are
converted into matter. As the universe expanded further, however, the
balance shifted. This happened when the universe was about a thousand
times smaller than at present. At that point, some photons escaped
absorption and scattering by electrons  indeed, they escaped the fireball
forever. We can still see these "fossil" photons. They are cosmic, arriving
from every direction in space (except for those blocked by the moon), a fact
which suggests that the universe "inflated" at that point rather than
scattering as in an explosion. The fossil photons wavelength has also
changed. They were originally released at a temperature of about
3000° K. but they have been severely red-shifted by gravity; from
originally having wavelengths like visible light, theyve shifted down into
microwaves.

Redshifts are the archetype of monetary inflation, shrinking the energy
content of the photon and thus shifting its color, just as if when the buying
power of a dollar bill shank, its color somehow gradually shifted from green
to yellow. These fossil photons are the afterglow of the infancy of the
universe, shrinking as their potential energy instead builds up. Should the
universe begin to collapse someday, the potential energy will be restored to
the photon, shifting its wavelength toward the blue end of the light
spectrum. To date, no one has seen any signs of a blue shift.

Its one thing to travel down a giant crack in the earth and see the
remains of ancient life fossilized in the rock. But to see light left over from
the early universe, fossilized as microwaves! This escaped radiation, still
rattling around the universe, marks the time at which hydrogen atoms were
first formed, the fireball of the expanding universe finally became
transparent, and light was no longer trapped in it.

One of the neurobiologists on our trip, a former physicist, told us the
story of the discovery of the fossil photons. The scientists who detected the
3° K microwave photons coming in from all directions in space were,
of course, quite concerned about false readings, particularly as flocks of
pigeons had adopted their horn-shaped antenna. Particularly when dealing
with signals near the noise level of the receivers and amplifiers, one has to
keep in mind that perhaps the "signals" are nothing but garbage fooling you.
The astrophysicists claim that, when contemplating the data, one of the
researchers said: "Either weve seen a pile of pigeon-shit or the creation of
the universe." The former possibility has now been eliminated; the
observations have been repeated many times in many places, with even
better equipment and fewer birds. You can even see them on a home TV set
 just tune to an empty channel and look at the "snow." About 1 percent
of the little "snow particles" are generated by cosmic photons left over from
the early universe becoming transparent.

Most of the original energy of the universe is now packaged as
particles  mass dominates the universe, though it may be converted back
into photons whenever some sort of transaction takes place and there are
some leftovers. Most of the mass is still in the form of hydrogen atoms. If,
however, the binding force between protons and neutrons were only a few
percent stronger, hydrogen would be unstable; as the physicist Freeman
Dyson once pointed out, that means that stars like our sun couldnt exist.
And there would be no water, a serious matter indeed to river-runners.

Hydrogen, it turns out, is the building block of the universe because
of what happens to hydrogen atoms when a lot of them coalesce to form a
star. All stars were initially great quantities of hydrogen held together by
gravity. Hydrogen has two "heavy" isotopes, deuterium and tritium; their
nuclei have a neutron or two in addition to the usual proton of the hydrogen
atom. Being neutral in charge, these extra neutrons attract no additional
electrons into orbit. But when these heavy hydrogen atoms collide with
each other at the 10- to 12-million degree temperatures found in the interiors
of stars, their nuclei may fuse, yield a new nucleus with a 2+2 configuration:
two neutral neutrons and two positive protons. This doubly-charged
nucleus naturally attracts two negative electrons into distant orbit. This
"doubled deuterium" is an atom of helium, and the process by which it is
formed is called fusion.

Some extra energy  I call it spare change  is given off in the process,
because the energy needed to hold together a helium nucleus is slightly less
than the sum of that for the heavy hydrogen nuclei (its somewhat the same
problem as trying to divide up $100 three equal ways youre going to need
some coins in addition to currency, and it still wont come out all equal).
This excess binding energy appears as photons of light. In fact, photons
such as this  after an eight-minute-and-twenty-second trip through space
 have inflicted more than one case of sunburn today. And that spare
change also heated up the rocks on which we sat to watch the stars.

Twinkle, twinkle little star,
I dont wonder what you are
For by spectroscopic ken
I know that you are hydrogen.
ANONYMOUS

We have mimicked the fusion furnace of stars here on earth. It is called
a thermonuclear reaction (though, in fact, little of the energy released by a
hydrogen bomb is from fusion: the great energy release of an H-bomb really
occurs because the fusion enables more of the uranium or plutonium of the
atomic bomb, which served as the trigger for the hydrogen, to be split).
E=mc^2 means that it takes only 1 gram of matter (a small coin
weighs about 2 or 3 grams) to release as much energy as there was in one
of the atomic bombs dropped in World War II. Someday, controllable
fusion (without a "dirty" fission trigger) will become a source of really cheap
and clean energy that could make coal and hydroelectric dams obsolete,
along with the present nuclear fission plants and their waste disposal
problems (instead, well have to worry about thermal pollution!). At least,
notes Dan Richard, there will be no Organization of Petroleum Exporting
Countries to control their fuel, seawater.

HEAVIER ELEMENTS LIKE CARBON, with its 6 protons and (usually)
6 neutrons, were not created in the Big Bang. And carbon is the prime
building block of life, so something else had to happen in between the early
universe and the evolution of life. The early universe expanded (and thereby
cooled) so fast that, by the time enough protons and neutrons were around,
it was too cool for building nuclei heavier than helium. Nor are heavy
elements created by fusion in ordinary stars like our sun whose packing
density remains too thin for heavy elements to begin forming. It really
requires an extraordinary packing density to make a heavy elements nucleus.
To make most elements requires the death of a star  a supernova.

A supernova doesnt last very long, but for days or weeks it may be so
much brighter than an ordinary star that it can be seen in the middle of the
day, a bright point of light in the blue sky. Our sun, it is said, can never
become a supernova. It isnt big enough. A supernova is created from a star
somewhat larger than our sun. After about 10 percent of its hydrogen has
been converted into helium, the star becomes unstable and eventually
collapses into a small, dense ball of matter (thus began the cliche, "The
bigger they are, the harder they fall"). As the star collapses, particles in it
move fast enough (another way of saying that the temperature is hot
enough) so that when helium nuclei collide, they can fuse to make carbon,
oxygen, and indeed all of the ninety heavier elements. Such fusions, of
course, release even more nuclear binding energy than the
hydrogen-to-helium conversion, the excess again appearing as light. And so
the supernova flashes into existence, lighting up the night sky and soon the
daytime sky with the spare change from the pressure cooker that is creating
heavy elements in the collapsing star.

It is supernovae that allow matter to evolve, that permit simple atoms
to become heavier atoms whose additional electrons in orbit allow the more
complex kinds of chemistry needed for life. The evolution of life can occur
only after the evolution of heavier matter. Had, however, the Newtonian
gravitational force constant been slightly different, all stars would instead
become either blue giants or red dwarfs, either too hot or too cool for most
scenarios allowing the evolution of life.

Now carbon and oxygen are the stuff on which the chemistry of life
depends. And with the exception of a few created here on Earth in bomb
tests, every one of the carbon atoms in our bodies and every bit of oxygen
we breathe got their start in a supernova. They were flung out into space by
the explosive collapse of the star, and later assembled into a planet. And
into us. A dramatist would say that stars have died that we might live.

No more than 6,000- to 7,000-million years ago, there was a supernova
nearby. Matter flung out from it eventually, under gravitational attraction,
began to cluster. Some of the hydrogen collapsed to such a density that the
hydrogen-to-helium conversion was ignited and our sun was born. That was
about 5,000-million years ago. At roughly the same time, other particles of
cosmic dust from "our" supernova and others coalesced into a giant disk of
swirling dust, spiraling around the sun. Eddies formed here and there, just
as in the river, and an eddy within the spiral disk was probably the focus for
the gravitational collapse of some dust into a compact ball. A planet. While
some planets developed hot interiors, none ignited. One of these planets,
third from the sun in distance, is the Earth; it went into business about
4,600-million years back.

The star of Bethlehem was the supernova of 6 B.C. recorded by the
Chinese astronomers (a monk counted incorrectly back in the Middle Ages,
when tallying up the elapsed years since the birth of Christ). If we had
stayed up long enough for Orion to rise in the eastern sky, we might have
seen the nearby Crab Nebula, the galaxy that was the site of a big supernova
back in the year 1054. It was so bright that the new star could be seen
during the daytime for weeks. But someone estimated that Orion wouldnt
rise until after four in the morning, and that it would be sunrise before it was
high enough in the sky to clear the eastern canyon wall.

We gave up before that. No comets, no supernovas, but a half-a-dozen
shooting stars as meteors tracked up the night sky. Still, not a bad day.

I DECIDED TO SLEEP on a rock ledge, something of a shallow cave,
because that was the best refuge in the sandstorm. And it beat putting up a
tent. Dan Hartline and I squeezed ourselves into a shallow cave where a
chunk of the canyon wall disappeared. Its really more of a ledge, with a
roof over it. Sitting up in bed is out of the question.

It took a long time to get to sleep. And then, out of the blue, someone
turned the lights on. As suddenly, I thought, as if someone were turning on
the bedroom lights in the middle of the night. Surely it wasnt sunrise yet.

It was the moon, shining into our cave. Id been in the shadows
up until a moment before. It took me several minutes to figure out how to
deal with this novel situation. Finally I put my sunglasses on. And tried to
get back to sleep. Moonglasses?